Method for rectifying objects such as dies of reducing rolling machines



May 12, 1970 R. R. L CHEL 510,995

METHOD FOR RECTIFYING JE S AS DIES OF R CING R0 NG MACH S Filed Aug. 15. 1966 I 2 Sheets-Sheet 1 May 12, 1970 R. R. L.'MICHEL 3,510,995

METHOD FOR RECTIFYING OBJECTS SUCH AS DIES OF REDUCING ROLLING MACHINES United States Patent ()lfice 3,510,995 Patented May 12, 1970 3,510,995 METHOD FOR RECTIFYING OBJECTS SUCH AS DIES F REDUCING ROLLING MACHINES Raymond R. L. Michel, Flohimont Par Givet, France, assignor to Trefimetaux, Paris, France, a French body corporate Filed Aug. 15, 1966, Ser. No. 572,458 Claims priority, application France, Feb. 16, 1966,

Int. Cl. 1324b 5/16 US. Cl. 51-327 3 Claims ABSTRACT OF THE DISCLOSURE Method for rectifying dies of reducing rolling machines, comprising rectifying simultaneously the two dles which are intended to work together and are mounted on their shafts in their relative working positions, wherein the shafts are made to undergo a movement of rotation about their axes and a horizontal movement of translation in a direction perpendicular to said axes and the grinding wheel is made to undergo a movement of rotation about its axis and a planetary movement of rotation of varying radius about a vertical axis, these various movements being so combined and synchronized as to achieve simultaneously the rectification of the two'grooves according a predetermined profile.

The present invention relates to methods of rectifying or grinding objects such as dies of reducing rolling machines.

In particular the working part of machines adapted to reduce by rolling, tubes, bars or like products, consists of dies of heat-treated steel which are mounted on shafts and on the periphery of which is formed at least one transverse pass or groove, the width and depth of which decrease on the same die from the start to the end of the rolling movement. These passes or grooves are roughly formed on lathes which are specially arranged for forming the decreasing section of the groove. After the dies have been heat-treated and mounted on the common shaft, it is necessary to rectifying their roughly formed groove so as to obtain the final profile. The profile or cross-sectional shape of the groove is usually non-circular and comprises a relieved or backed-off portion on each of the edges of the groove to facilitates the deformation of the metal in the course of rolling.

Further, in view of the fact that the dies work in pairs, it is desirable to effect a simultaneous rectification of the dies of the same pair intended to cooperate after mounting on two parallel working shafts of the reducing machine. Indeed, if the grooves or recesses of the dies are not exactly facing each other and are not exactly identical, axial forces are created which shorten the life of the dies and affect the precision of the reduction. This drawback is more serious when, as is usually the case, several dies are mounted on the same shaft so that the parasitic forces could reach an abnormally high value.

According to the rectification method usually employed up to the present time, the die is mounted on a kind of lathe and undergoes a uniform rotational motion in front of a carriage on which is fixed a rectifying grinding wheel having round edges. The carriage undergoes combined motions of translation and oscillation which usually permit the grinding wheel to rectify the profile of the groove.

Thismethod has serious drawbacks: It does not permit rectifying any type of pass or groove and in particular a groove mentioned hereinbefore which comprises backedofi portions. It does not permit rectifying simultaneously two dies which must be coupled on the reducing machine and it is moreover impossible on the machines employed,

to rectify the dies mounted on their working shaft. Thus, it is impossible by the conventional method to re-condition used dies, the latter usually being mounted on their working shaft after heat treatment which render their disassembly if not impossible at least very difiicult.

In order to remedy the various drawbacks mentioned hereinbefore, the object of the present invention is to provide an improved method of rectifying objects, such as dies of reducing rolling machines, said objects comprising on their periphery at least one transverse grOOVe or pass and being adapted to operate in pairs. Said method comprises rectifying simultaneously the two objects which are intended to work together and are mounted on their shafts in their relative working positions.

'In practice, the two shafts are disposed horizontally in parallel and side-by-side relation, said shafts carrying in facing relation and in their relative longitudinally and angular positions of work the two objects to be rectified, a cylindrical grinding wheel having a vertical axis and a diameter less than the smallest diameter of the groove in the narrowest part thereof, is disposed between said objects in the grooves to be rectified, the shafts are made to undergo a movement of rotation about their axes and a horizontal movement of translation in a direction perpendicular to said axes and the grinding wheel is made to undergo a movement of rotation about its axis and a planetary movement of rotation of varying radius about a vertical axis, these various movements being so combined and synchronized as to achieve simultaneously the rectification of the two grooves according a predetermined profile.

Among other advantages, this method permits simultaneously rectifying in pairs dies mounted on their respective working shafts and rectifying grooves having any cross-sectional shape, that is, having, if desired, relieved, or backed-off portions.

The method also permits employing commerciallyavailable cylindrical grinding wheels and no forming or diamond dressing-thereof is necessary until complete wear of the grinding wheels.

Another object of the invention is to provide a machine for carrying out theaforementioned method, said machine comprising in combination a stand: a support device supporting die-carrying shafts, a device for rotating said shafts, adevice causing said shafts to move horizontally in translation, a planetary spindle carrying device, a cylindrical grinding wheel mounted on said spindle and rotated about its axis, a device effecting the movement for varying the ofiset of said spindle, and a single drive mechanism for synchronizing the three movements.

Independently of the aforementioned movements, a device is provided for vertically and horizontally shifting the spindle carrier in a precise manner.

Further features and advantages of the invention Will be apparent from the ensuing description, with reference to the accompanying drawings to which the invention is in no way limited.

In the drawings:

FIG. 1 is a perspective view of a die Which can be rectified by the method according to the invention;

FIG. 2 is a cross-sectonal view in the plane of symmetry of said die;

FIG. 3 is a diagrammatic sectional view of the crosssectional shape of the associated or cooperating grooves of two dies and the working position of the grinding wheel between said dies;

FIG. 4 is a view similar to FIG. 3 showing operation of the grinding wheel in the course of rectification of the backed-off or relieved portions of the grooves;

FIG. 5 is a perspective view, with parts cut away, of the rectifying machine according to the invention;

FIG. 6 is a detail view of the planetary spindle carrier arid grinding wheel, and

FIGS. 7, 8 and 9 are diagrams showing the work effected by the grinding wheel respectively in the course of one cut, from one cut to the next, and in the course of the last cut.

The rectifying method according to the invention permits rectifying in particular the dies of reducing machines such as that shown in FIG. 1. This die 1 consists of a cylinder 2 on the periphery of which is formed a groove 3 whose section decreases from the section a corresponding to the start of the rolling to the section b corresponding to the end of the rolling. This groove subtends an angle at the centre of about 300 and at point 0, between a and b, the recess is deeper so as to permit the advance of the product in the course of the reducing operation between two successive rollings.

FIG, 2 is the sectional view of the die 1 taken on its plane of symmetry and FIG. 3 is a sectional view of the groove 3 in a plane intersecting the axes of two dies. In the illustrated example the groove 3 comprises a part-circular portion 4 and two lateral backed off or relieved portions 5 which are also part-circular but have a slightly greater radius so as to facilitate the deformation of the product being reduced.

The machine for carrying out the method according to the invention, in the particular case of the rectification of the dies of a triple reducing machine, will now be described with reference to FIG, 5 which is a diagrammatic perspective view of this machine.

The machine comprises a stand 6 having a base 7, and two vertical uprights 8 and 9 interconnected by a horizontal member 10. Disposed on the base 7 are two slideways 11 and 12 on which are movable four carriages 13, 14, 15 and 16 which directly support the blocks receiving the bearings 17 and 18 of the die-carrying shafts.

Journalled in these bearings by their journals 19 and 20 are two parallel shafts 21 and 22 each of which carries, in the illustrated embodiment, three dies, each die 23, 24 and 25, of the shaft 21 being located in front of the corresponding die, 26, 27 and 28, of the shaft 22. The shafts 21 and 22 are the complete shafts of a reducing machine, the dies 23 28 are consequently arranged in pairs in the positions corresponding to their working positions in the reducing machine.

Mounted on the horizontal member is a planetary spindle-carrying device 29 which is movable horizontally along this member by a mechanism of known type (not shown) and vertically by a hand-wheel 30, The device 29 can be locked in posiiton by two jacks 31 supplied with compressed air at constant pressure.

The device 29 (FIG. 6) is known in the art and comprises a spindle 32 carrying a cylindrical grinding wheel 33. The spindle undergoes a planetary movement of rotation about an axis XX whereas the grinding wheel 33 rotates about its axis YY which is offset from the axis XX.

The spindle carrier 29 is mounted on the member 10 in such manner that the axis XX remains in the vertical plane of symmetry parallel to the axes of the diecarrying shafts.

The planetary movement of rotation is effected at a variable radius and the device which controls this variation in radius will be described hereinafter.

The mechanism producing and synchronizing the various movements comprises: a motor-speed variator unit 34 which drives the shafts 21 and 22 in rotation through reducing gears 35, 36 and two homokinetic joints 37. The same motor-speed variator unit 34'also drives a cylindrical cam 41 through gears 38, 39 and 40, this cam cooperating with a cam-follower roller 42 for the purpose of controlling the parallel and symmetrical spacing or distance between the shafts 21 and 22 through two earns 43 which have a rectilinear profile and are mounted on a rod 44. The cams 43 cooperate with rollers 45 connected to the carriages 13, 14, 15 and 16, Springs 46 and 47 bias the carriages and the rod 44 towards the position which corresponds to the bearing of the roller 42 on the cam 41.

Two pairs of bevel gears 48, 49, a homokin'etic joint 50, a sleeve 51 and a splined rod 52 slidably mounted in the sleeve 51 connects the unit 34 to a cam 53 for rotating the latter, this cam controlling the eccentricity or olfset of the spindle 32 (FIG. 6).

The cam 53 cooperates with a roller 54 mounted on a lever '55 which carries at one end a counterweight 56, pivots about a pin 57 carried by a support 58 and carries at its other end a rod 59.

Depending on the position of the cam 53, the rod 59 moves vertically between the two extreme positions shown in the drawing (FIG. 6) and its vertical movements are converted into horizontal movements in the known manner in the device 29, so as to vary the eccentricity or offset of the spindle 32. The planetary spindle known under the trade name Piat could be employed for converting these movements.

The grinding wheel 33 has a small diameter and it is therefore possible to employ for feeding the motor of the planetary rectification or guiding spindle a frequencychanging unit (placed adjacent the machine but not shown in the drawing). This unit ensures a rotational speed of the grinding wheel of around 15,000 rpm. The rotation of this spindle about the axis XX is obtained by means of a motor and a planetary speed reducer housed in the column of the spindle carrier 29.

The machine just described operates in the following manner:

The two associated shafts 21, 22 of a reducing machine, on which are fitted the dies whose grooves were roughly shaped on a lathe, are mounted with their bearings and blocks on the carriages 13, 14, 15 and 16, the axes of the shafts being horizontal and parallel so that on the facing cylindrical faces of the dies the sections of the grooves increase in size in the upward direction.

The grinding wheel-carrying spindle 32 is placed in its correct working position, namely in the space defined by the grooves of the two associated dies 24 and 27, for example as shown in FIG. 5.

With the grinding wheel in position, the motor-speed variator unit 34 is started up to rotate the shafts 21 and 22, shift them horizontally and render the spindle offset or eccentric and the two motors rotating the grinding wheel on its axis and causing its planetary movement are also started up. The cams 41 and 53 are so designed, bearing in mind the slope of the cams 43, as to obtain the predetermined profile 4 of the groove in the dies. The grinding wheel, in grinding the portion 4 of the groove, operates in the manner shown diagrammatically in FIG. 3, that is, it rotates about itself and about the axis XX and generates a cylinder whose radius is a function of the angular position of the dies. It rectifies the two associated dies 24, 27 simultaneously.

The rectification or grinding of the backed-off portions 5 of the profile is effected in a similar subsequent second operation (FIG. 4) in first replacing the cams 41 and 43 by other cams having suitable profiles.

In a general way, in the course of each travel or cut, the dies rotate in descending towards the grinding wheel and they present to the grinding wheel groove profiles which increase in size.

In respect of the first grinding cut or travel, that is, of the first rotation of the dies, the spindle-carrying assembly is lowered vertically until the grinding wheel comes in contact with the metal in excess. This contact occurs at the lower end 60 of the grinding wheel (FIG. 7 In the course of this cut or travel and in the course of each following cut, the grinding wheel advances horizontally and works mainly in its cylindrical part, the cutting angle [3 varying but slightly from the beginning to the end of a cut.

However, the grinding wheel becomes worn in the course of each cut or travel and its end assumes a more or less frusto-conical shape.

When the dies have eifected a complete rotation and present their part c in front of the grinding wheel (FIG. 8), the spindle carrier is lowered such height h as to compensate the wear of the grinding wheel and to remove a thickness of metal corresponding to the following cut or travel; the cutting angle, which was 3,, in the course of the preceding cut, becomes B +1 B Thus from one cut to the next, the cutting angle decreases so that the grinding wheel does not operate at the start of this new cut in its conical part, which is worn in accordance with an angle p but in its cylindrical part. In the course of this new cut, the wear of the grinding wheel continues in a similar manner, the large base of the frusto-conical portion being formed slightly higher on the grinding wheel than that which was produced in previous cut.

The operation is pursued in the same manner in respect of the following cuts, the angle 3 between the generatrix of the cylindrical surface of the grinding wheel and the tangent to the groove at the point of contact with the grinding wheel obtained in the diametral plane of the grinding wheel intersecting this point of contact decreasing from one cut to the next.

The part of small diameter of the frusto-conical region of the grinding wheel becomes progressively inoperative whereas the region adjacent the large wheel operates only in its heretofor unused cylindrical lateral surface (FIG. 9), the cutting angle 8 being nil.

It is clear from the foregoing that the cylindrical grinding wheel can be employed throughout its length without need to diamond dress the wheel in the course of operation. This is a very important advantage of the invention over the conventional method from the point of view of simplicity of operation and cost price.

When a pair of dies has been ground, it is suflicient to raise the device 29, shift it along the member 10 and place it in front of a new pair of dies to be ground.

The appearance of the thus ground surfaces of the grooves or passes is of course dependent on the grain size of the grinding wheels employed. For example with grinding wheels having a grain size of 60 or 80, the state of the surface is such that a simple longitudinal polishing eliminates the transverse traces of grinding.

It will be understood that, as in any grinding operation, the work is carried out with an abundant spraying of the workpiece and grinding wheel. The spraying device is known in the art and has not been shown in the drawing in order to render the latter more clear.

Although specific embodiments of the invention have been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

For example, by providing the cams 41 and 53 with an appropriate profile, it is possible, by means of the method and machine according to the invention, to rectify or grind any type of groove, pass or the like employed for the dies of reducing machines and whose successive cross-sectional shapes can vary in a progressive manner from one end to the other of the groove.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. A method for rectifying objects, such as dies of reducing rolling machines, having on their periphery at least one transverse groove, wherein the two objects, which are intended to operate together, are rectified simultaneously and are mounted on two shafts in their relative longitudinal and angular working positions and a cylindrical grinding wheel having a vertical axis and a diameter less than the smallest diameter of the groove in the narrowest part thereof is disposed between said objects in the grooves to be rectified, said method comprising rotating the shafts about their axes and moving the shafts horizontally in a direction perpendicular to said axes and moving the grinding wheel about a vertical axis at a varying radius from the vertical axis, said various movements being so combined and synchronized as to achieve simultaneously the rectification of the two grooves according to a predetermined profile.

2. A method as claimed in claim 1, wherein the objects to be rectified are dies of reducing rolling machines and comprise at least one groove whose cross-section decreases from a section corresponding to the start of rolling to a section corresponding to the end of the rolling, the profile of said groove being rectified by successive cuts of the grinding wheel, the angle between a generatrix of the grinding wheel and the profile to be rectified decreasing from one cut to the next.

3. A method as claimed in claim 2, wherein in order to compensate the wear of the grinding wheel in the course of the successive cuts and to ensure the advance of said grinding wheel for each cut, said grinding wheel is lowered to such extent as to once more bring the grinding wheel in the correct working position, the final cut being effected by the cylindrical part of the grinding wheel which has not yet been utilized.

References Cited UNITED STATES PATENTS 1,361,850 12/1920 Guild 51-90 1,404,691 1/1922 Gail 51 9 0 2,715,806 8/1955 Hancock 51-90 X 3,105,413 10/ 1963 Lanzenberger.

ROBERT C. RIORDON, Primary Examiner D. G. KELLY, Assistant Examiner U.S. Cl. X.R. 5l90 

